This invention relates to filter driers and in particular, to a filter drier having utility in heat pump applications. While the invention is described in detail with respect to such filter drier use, those skilled in the art will recognize the broader applicability of the inventive concepts disclosed hereinafter.
Reversed cycle refrigeration systems, more commonly known in the art as heat pumps, have become increasingly popular because of their ability to use existing equipment efficiently for both heating and cooling. The use of filter driers to remove contaminants such as solid particles, water, acid, oil-oxidation products and waste from refrigeration systems is an accepted method of maintaining performance of those systems. Before the widespread use of reverse flow refrigeration systems or heat pumps, fluid flow always has occurred in one direction through the closed loop system. No difficulty is experienced in designing reliable means for trapping the solid contaminants within the body of the filter and keeping them there with single direction flow. However, the reversal of fluid flow required by heat pump systems means that the contaminants are flushed back out of the filter and thus, the filter is only a temporary collector of contaminants.
A number of expedients have been employed for overcoming the problem of reversed flow in heat pump applications, with varying success. One solution was to filter the fluid in one direction of flow only, and to bypass the filter when reversed flow was required. Another solution used in the art is to arrange two filters in parallel with suitable check valves to filter the flow in both directions of flow. While the two filter method is an improvement over the filter bypass method, it does require two filter elements for its implementation. Thus, it intrinsically is expensive in use.
The invention disclosed hereinafter overcomes these prior art difficulties by providing a self-contained valve assembly and filter unit using a single filter element, that element trapping and retaining particulate contaminants regardless of the direction of fluid flow at the input and the output of the filter unit.
Various valving arrangements are known in nonanalogous arts. For example, the U.S. Pat. No. 3,200,255, to Masuda, issued Aug. 10, 1965, discloses an ocean wave electric generator employing a flapper valve arrangement for channeling air through a turbine generator. Our invention is distinguishable from the Masuda disclosure in a number of structural areas, although it does utilize a flow direction pattern similar to that disclosed in Masuda.
One of the objects of this invention is to provide a self-contained filter unit that will trap and retain particulate contaminants regardless of the direction of fluid flow into the filter unit.
Another object of this invention is to provide a bi-flow filter unit employing a single filter means in a self-contained enclosure.
Another object of this invention is to provide a low cost filter for heat pump applications.
Yet another object of this invention is to provide a self-contained filter unit in which fluid flow through the filter element is unidirectional although input to the filter unit is bi-directional.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.